Within the human body are various passages, which convey fluids. Material may build up on the walls of such passages such that partial blockages may occur. Indeed, such partial blockages, if left untreated, may eventually become complete blockages. Whether the blockages are partial or complete, there usually are adverse health consequences associated therewith.
In the cardiovascular system, in particular, a vein or artery may be partially or completely blocked. The veins or venous blood vessels may be blocked (hereinafter meaning partially or completely blocked) by a blood clot called a thrombus. The arteries or arterial blood vessels may also be blocked by a thrombus. In either a vein or artery, plaque or other such blockages should be treated using one or more medical procedures.
The following patents are noted:
InventorPatent No.Issue DateAuth4,445,509May 1, 1984Auth4,646,736Mar. 3, 1987Summers4,850,957Jul. 25, 1989Stack et al4,867,156Sep. 19, 1989Auth4,990,134Feb. 5, 1991Stack et al5,059,211Oct. 22, 1991Stack et al5,306,286Apr. 26, 1994Auth et al5,314,407May 24, 1994Auth et al5,364,393Nov. 15, 1994Cragg5,370,653Dec. 6, 1994Abela5,895,400Apr. 20, 1999
The Stack patents disclose catheters for removing plaque from the wall of an artery using blade elements and devices to work with such cutting catheters.
The Auth patents show various structures for removing calcified material. The use of diamond dust covered abrasive devices, a cutting tool with spirally shaped cutting flutes, and electrical ablation are among the techniques disclosed.
The Cragg patent and the Summers patent both show cutting catheter systems and methods. Cragg has rotatable soft flexible bristles, whereas Summers has a cutting arrangement with a continuous filament brush and an alternate cutting blade design.
The Abela patent discloses a catheter with a rotatable bristle arrangement carried on a sweep catheter extending along a guide wire.
Cutting devices often must be sized to fit the particular passage which is being treated. In other words, one must use a different size cutter for every different size of vessel. Disadvantageously, one must then have more than one cutter available and must determine the correct size before putting the cutter into the patient, such that the correct size cutter is used. Use of a cutter that is too small will not remove all of the plaque or other built-up material. Use of a cutter that is too large increases the chances of damaging healthy tissue on the wall of the passage.
Some prior devices for cutting or removing material from the walls of passages in a patient are constructed such that they may damage healthy tissue on the wall of the passage even if they are the right size. Depending on the characteristics of the blocking material, the adjacent healthy tissue, and the cutting device (for example, if the cutting device is too rigid), damage may occur when cutting.
A further problem with some prior arrangements is that materials removed from the wall of a blood vessel, for example, can create problems downstream from the original blockage. Removed materials can resettle downstream and create a partial or complete blockage at a new location. Depending on the size of the material pieces, a heart attack, stroke, or other health problems can result from attempting to remove blood vessel obstructing material.
Chemical solutions have been proposed for use in dissolving the pieces. Depending upon the chemical used, this may require that the passage be blocked by a balloon for a considerable period of time. A catheter-controlled balloon may be used downstream from where the material is being removed. The balloon prevents removed material from passing by it until the material is dissolved. Suction devices have also been used for removing material.
The Abela patent discloses a catheter system that overcomes several of the disadvantages found in prior devices. A sweep catheter having a set of bristles on its distal end is proposed for use in removing all or portions of a thrombus located in a vein or artery. This system is effective at removing the material while eliminating or reducing the risk of damage to blood vessel tissue.
Accordingly, a catheter system and method that addresses one or more of the above-noted deficiencies or disadvantages would be desirable.